https://github.com/golang/go/issues/33167
On Sunday, July 12, 2020 at 10:44:02 PM UTC+2 [email protected] wrote: > On Sun, Jul 12, 2020 at 9:33 PM Bakul Shah <[email protected]> wrote: > >> On Jul 12, 2020, at 11:11 AM, Gert <[email protected]> wrote: >> > >> > https://play.golang.org/p/6xMgjr1IyFD >> > >> > var fn myHandler >> > fn = func(w http.ResponseWriter, r *http.Request) { >> > fn.GET(w, r) >> > } >> > >> > Just wondering if it's possible somehow to write this in one line like >> so >> > >> > var fn myHandler = func(w http.ResponseWriter, r *http.Request) { >> > fn.GET(w, r) >> > } >> >> The issue is that fn's type can't be completely determined until >> the RHS func is fully analyzed but for that to work fn must be >> known! > > > Why? ISTM the type is mentioned twice - once as "myHandler" on the LHS and > once in the signature on the RHS. And there isn't even a way to write down > a function literal without mentioning the full type. On the surface, this > seems like a relatively straightforward scoping issue, introduced by the > fact that the scope of a variable declaration starts at the end of it's > VarSpec, not the "=". Interestingly though, the initialization rules > prevent this from working at the package-level, where this scoping problem > doesn't exist: https://play.golang.org/p/IPMxtYETGsg > > Also note that the first definition won't do what you may be thinking >> it does. The`fn.GET` call will be to the existing value of fn, not >> the result of the assignment. >> > > No, it won't. The function-literal closes over `fn`, so it will use > whatever is assigned at call-time. > https://play.golang.org/p/VCvCt8J8Zcw > I use this pattern all the time to define a recursive function without > polluting the package-scope. > > >> -- >> You received this message because you are subscribed to the Google Groups >> "golang-nuts" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/716C7D59-9F2B-4AAD-8560-79011359A96C%40iitbombay.org >> . >> > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/acbc2cad-163d-461a-a546-5a8248d0c392n%40googlegroups.com.
